Sunday, September 11, 2005

Degrees, Minutes & Seconds

While calibrating images to add its corresponding geographic references you need to provide a specific point in the surface of the Earth. There are at least three ways of describing them:

  • Degrees (DD.DDDD)
  • Degrees, Minutes (DDMM.MMMM)
  • Degrees, Minutes and Seconds (DDMMSS.SS)
Where

1 degree = 60 minutes = 3,600 seconds

or 1° = 60' = 3,600"

  • To convert from Degrees to Degrees and Minutes

122.37° = 122° (0.37 * 60') = 122° 22.2'

  • To convert from Degrees and Minutes to Degrees, Minutes and Seconds

122° 22.2' = 122° 22' (0.2 * 60") = 122° 22'12"


If you want to go the other way around, like converting seconds to minutes you need to multiple your seconds by 1'/60" (from above 1' = 60') so

12" x 1' / 60" = 12 x 1' / 60 = 12/60 x 1' = 0.2'


Similar process to convert minutes to degrees

22.2' x 1° / 60' = 22.2 x 1° / 60 = 22.2/60 x 1° = 0.37°

You can also use some JavaScript-based calculators if this looks too much.